Battery

ABSTRACT

An object is to limit temperature rise in a battery, which operates at ambient temperature, due to heat generated at an outside heat source mounted close to the battery. A hollow space is formed in a wall of a battery container or a heat insulating material is mixed in a resin of the battery container, thereby enhancing the heat insulating effect of the battery container. Of the outer surface of the battery container, a portion adapted to be in contact with a battery-supporting member is provided with projecting extensions or protuberances and depressions so that heat generated outside of the battery is prevented from being transferred by conduction. A shield member is disposed on the outer surface of the battery container so that heat transfer to the battery by radiation is prevented.

FIELD OF THE INVENTION

The present invention relates to a battery mainly using, as electrolyte,a dilute sulfuric acid, a caustic alkaline solution, a nonaqueoussolution or the like, which operates at ambient temperature (a batterythat operates at ambient temperature is herein meant a battery that iscapable of operating at ambient temperature or lower and is intended tobe generally operated at ambient temperature), and more particularly abattery to be mounted in proximity to a heat generating source, such asin an engine room of an automobile.

BACKGROUND OF THE INVENTION

For example, a lead-acid storage battery for automobile use is mountedinside the hood. An engine as a heat generating source is also mountedinside the hood. Heat generated at the heat generating source istransferred by radiation or conduction into the battery, therebyincreasing the temperature of the battery.

Increase in temperature of the battery makes electrolyte easy toevaporate so that the amount of electrolyte loss in the battery may beincreased. For a lead-acid storage battery, as the amount of electrolyteis decreased, the concentration of sulfuric acid of electrolyte isincreased. This may lead to shortening the serviceable period of thebattery or disable the battery to discharge a given level of electricitywhen the solution level is lowered and hence battery plates are exposed.

As another disadvantage, the amount of self-discharge is increased asthe temperature of the battery is increased.

Conventionally, no attempts were made to positively prevent heattransfer from an outside heat source to a battery. Therefore, for amonoblock-type lead-acid storage battery for automobile use, the cellsat the both ends of the battery, to which heat from the outside is easyto conduct, increase their temperatures and cause a great amount ofelectrolyte loss as compared with inner part located cells. This leadsto a drawback, causing variation in battery performance among the cellsand great deterioration of the cells of the both ends of the battery.

The present invention has been conceived in consideration of the abovedrawbacks. It is an object of the present invention to provide for aprevention means for preventing heat generated at an outside heat sourcefrom being transferred by radiation or conduction into the battery.

SUMMARY OF THE INVENTION

A battery of the present invention is characterized in that it includesa battery container made of synthetic resin, wherein a wall of thebattery container has a hollow space therein or a plate made ofsynthetic resin with a hollow space therein is attached to an outersurface of the battery container. This battery can prevent heatgenerated at an outside heat source from being transferred into thebattery by conduction.

A battery of the present invention is characterized in that it includesa battery container made of synthetic resin and a plate made ofsynthetic resin, in which the plate is attached to an outer surface ofthe battery container so as to have a hollow space therebetween. Thisbattery can prevent heat generated at an outside heat source from beingtransferred into the battery by conduction.

A battery of the present invention is characterized in that it includesa battery container, in which the battery container is made of syntheticresin and a heat insulating material is mixed in the synthetic resin, ora heat insulating material is mixed in a plate made of synthetic resin,in which the plate is attached to an outer surface of the batterycontainer. This battery can prevent heat generated at an outside heatsource from being transferred into the battery by conduction.

A battery of the present invention is characterized in that it includesa battery container made of synthetic resin, in which projectingextensions or protuberances and depressions are provided on a portion ofan outer surface of the battery container, which portion being adaptedto be in contact with a battery-mounting member. This battery canprevent heat from being transferred to a body of the battery container.

A battery of the present invention is characterized in that it includesa battery container and a shield member disposed outside of the batterycontainer so as to block radiation heat transfer. This battery canprevent radiation heat transfer from an outside heat source to thebattery container.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an appearance of a battery with a side wall sectioned,according to one embodiment of the present invention.

FIGS. 2A and 2B each illustrate a schematic appearance of the batterywith a side wall sectioned, according to one embodiment of the presentinvention.

FIG. 3 is a view illustrating an appearance of a battery containeraccording to one embodiment of the present invention.

FIG. 4 is a view illustrating an appearance of a battery containeraccording to one embodiment of the present invention.

FIG. 5 is a view illustrating an appearance of a battery containeraccording to one embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, the description will be made for an embodiment of the presentinvention by taking for example a lead-acid storage battery forautomobile use, which produces a remarkable effect.

According to a first embodiment of the present invention, a batterycontainer is provided with a wall that itself has heat insulationcapability, or has a heat insulating material attached to an outersurface of the battery container by such as bonding or fittingengagement so as to prevent heat generated outside of the batterycontainer from being conducted into the battery. For this, specifically,a hollow space is formed in a wall of the battery container made ofsynthetic resin or formed in a plate made of synthetic resin disposed onthe outer surface of the battery container. Various means such asbonding or a structure enabling fitting engagement may be employed toachieve attachment of an insulating material.

Preferably, powdered insulating material is sealed in the hollow space.

FIG. 1 is a view illustrating one form of a lead-acid storage battery 1according to the first embodiment of the present invention. A batterycontainer is made up of a battery case 2 having a side wall and a bottomwall, and a lid 3 acting as a top wall. Reference numerals 4 and 5respectively represent a positive terminal and a negative terminal. Thebattery case 2 and the lid 3 are made of ABS resin, which is a copolymerof acrylonitrile, butadiene and styrene, or polypropylene (PP) resin.

Of the battery case 2 and the lid 3, the battery case 2 directlycontacts a plate pack and electrolyte and therefore it is effective toenhance the insulating capability of the wall surface of the batterycase 2.

FIG. 1 illustrates a side wall 6 of the battery case 2 in section.

The side wall 6 defines therein a hollow space 7, as illustrated in FIG.1.

Gas (generally air), or powdered insulating material such as perlite orsilica aerogel is sealed in the hollow space 7 so as to prevent thehollow space from being crushed by outside force. The thus providedhollow space enhances the heat insulating capability of the side wall.

In FIG. 1, the hollow space 7 is formed only in the side wall of thebattery case 2, while it is also effective to form a hollow space in thebottom wall of the battery case 2.

In FIG. 1, one large continuously formed hollow space is illustrated.Alternatively, it is possible to employ a wall made of synthetic resinby using plastic foam in which minute hollow spaces are distributed.

As plastic foam for the battery container, hard foam is suitable.Accordingly, it is possible to apply hard foam such as styrene resin andvinyl chloride resin, as well as the ABS resin and the PP resin.

In another embodiment associated with the first embodiment, a syntheticresin plate having a hollow space as shown in the above embodiment isattached to an outer surface of a battery container by such as bondingor fitting engagement. As such, various attaching means such as bondingor a structure enabling fitting engagement may be employed. For example,it is possible to employ an arrangement where the outer surface of thebattery container has grooves or recesses into which a resin plate orthe like is fitted.

For the synthetic resin plate, the same material used for thesynthetic-resin-made battery case is applicable. While the platethickness is not necessarily limited to a specific thickness, a platehaving a large thickness can produce a high insulating effect.

However, a thickened insulating plate material may cause a problem ofoccupying a great space. In consideration of this, the thickness of aplate material is preferably 1 mm-10 mm.

When a heat insulating material is sealed in the hollow space, theinsulating capability can be further enhanced.

This insulating material sealed in the hollow space can maintain thestrength of the synthetic resin plate.

Another embodiment associated with the first embodiment is illustratedin FIG. 2.

A battery as illustrated in FIGS. 2A and 2B has a synthetic resin plate14 mounted thereon by such as bonding or fitting engagement in such amanner as to have a hollow space along the outer surface of the batterycontainer. The synthetic resin plate 14 may have projecting extensions,or protuberances and depressions on the surface thereof contacting thewall of the battery container, as illustrated in FIG. 2B. The shape ornumber of the projecting extensions or protuberances and depressions arenot necessarily limited to specific ones. These projecting extensions,or protuberances and depressions can maintain the strength of thesynthetic resin plate.

When a heat insulating material is sealed in the hollow space, the heatinsulating capability can further be enhanced.

In another embodiment associated with the first embodiment, a heatinsulating material may be mixed in a synthetic resin of the batterycontainer of FIG. 1, or in a synthetic resin of a heat-insulatingsynthetic resin plate which is mounted to the outer surface of thebattery container by such as bonding or fitting engagement. For example,it is possible to employ a mounting means such as snap-fitting, which isrealized by recesses formed in the outer surface of the batterycontainer, into which a resin plate having a heat insulating material ina synthetic resin thereof is snap fitted.

The heat insulating material may be in powdered or fibrous form. While amaterial is not necessarily limited to a specific one, know materialssuch as alumina hollow ball, zirconia hollow ball, diatomaceous earthand calcium silicate, as well as the perlite and the silica aerogel maybe used as powdered heat insulating material. For a good insulatingperformance, it is preferable to add 30-60 volume % of a heat insulatingmaterial to the aforesaid resin.

Now, the description will be made for a second embodiment with referenceto FIG. 3.

According to the second embodiment of the present invention, heatconduction through the outer surface of the battery container isprevented. Specifically, a contacting area of the battery container witha battery-mounting base is minimized by providing projecting extensions,or protuberances and depressions to the outer surface of the batterycontainer.

FIG. 3 illustrates an outer surface of a lead-acid battery according tothe second embodiment of the present invention. Projecting extensions 8provided on a bottom surface and lower portions of a side wall of thebattery case 2 minimize a contacting area of the battery case 2 with abattery-mounting base 9. This prevents heat from conducting to thebattery case 2 through the base.

Herein, the description was made by taking for example a case where theprojecting extensions are provided on the outer surface of the batterycontainer. Protuberances and depressions in place of the projectingextensions can also decrease the contacting area of the batterycontainer with the base. The number or shape of the projectingextensions, protuberances and depressions, etc. are not necessarilylimited to specific ones. It is preferable to employ an arrangement thatprovides such a degree of the mechanical strength as to secure apredetermined space between the battery container and thebattery-mounting base, while minimizing the contacting area of thebattery container with the battery-mounting base.

Now, the description will be made for a third embodiment with referenceto FIG. 4.

According to the third embodiment of the present invention, heattransferred by radiation from a heat source to the battery case 2 isprevented. For this, a shield member that blocks radiation heat transferis provided between a battery container and a heat source. Asillustrated in FIG. 4, in this embodiment, a shield member 10 made ofmetal is disposed so as to face the direction from which radiation heatcomes.

The shield member is of a plate-like shape and fixed to the batterycontainer through a support member 11 so as to extend along a side wallof the battery container with a clearance therebetween.

As the shield member 10, it is possible to employ a plate of metal suchas aluminium, stainless steel or nickel, a plate of synthetic resin suchas polypropylene or other white opaque resin or a plate of ceramics suchas alumina, or a composite material that is formed with a metal layersuch as aluminium by vapor-depositing or applying foil to a syntheticresin plate or a ceramic plate by such as bonding or fitting engagement.This shield member may be attached to the surface of the batterycontainer by such as bonding or fitting engagement. As attaching means,various means may be employed as described above.

The shield member preferably has a smooth surface for improvedefficiency in reflecting radiation heat.

According to another preferable form of the third embodiment of thepresent invention, the battery container is designed to give aradiation-heat shielding function to a radiation-heat receiving portionof the outer surface of the battery container.

Specifically, metal foil is attached to the outer surface of the batterycontainer by such as bonding or fitting engagement, or a resin platehaving a metal layer such as a metal foil, a metal sprayed film or avapor-deposited film is attached to the outer surface of the batterycontainer by such as bonding or fitting engagement.

The metal layer is proper as a shield member to be directly placed onthe surface of the battery container since it is flexible and thereforeunlikely to be damaged due to deformation of the battery container, andprovides an excellent heat-shielding performance.

Metal is not necessarily limited to a specific one, while aluminium issuitable because it is of a light weight and provides an excellentradiation-heat reflection performance. However, a shield member of metalis likely to be corroded when electrolyte touches it. Aluminium also hasa shortcoming that it has a poor mechanical strength and therefore iseasy to be damaged.

Accordingly, in a case where a shield member made of a metal layer isemployed, it is preferable to coat the surface of a metal shield memberwith a transparent protecting film in order to overcome the shortcoming.

Specifically, a metal layer is first formed on the outer surface of abattery case of synthetic resin by vapor-depositing or applying foil bysuch as bonding, and then the surface of the metal layer is coated witha transparent resin film such as polyester having a thickness of severaltens μm to several hundreds μm. Or, a vapor deposited film formed byvapor-depositing aluminium to the surface of a polyester film, or alaminate film formed by laminating aluminium foil to a polyester film ora nylon film is attached to the outer surface of the battery containerby such as bonding or fitting engagement, with an aluminium layer of thevapor-deposited film or the laminate film held in contact with the wallof the battery container.

FIG. 5 is a view illustrating an embodiment, in which an aluminium orother metal layer 12 as a shield member is formed on the surface of thebattery case 2. A protection film 13 made of the aforesaid resin isformed on the wall of the battery case 2 by the aforesaid method so asto cover the metal layer 12 and the wall of the battery case 2. Themetal layer 12, which is formed by the vapor-deposition or lamination,preferably has a thickness of 5 μm-200 μm for ease of forming, while notlimited to a specific thickness, as long as it has a capability toreflect radiation heat.

A shield member against the radiation heat is not required to bearranged entirely on the outer surface of the battery container, as longas it is arranged on the side to which heat is radiated. For a lead-acidbattery, an alkaline battery or the like, the wall of the batterycontainer is entirely or partially transparent or semi-transparent toprovide an observation window through which the electrolyte level isobserved. Accordingly, it is preferable to locate the synthetic resinplate, the heat insulating material and the shield member so as not tobe overlapped with, for example, the electrolyte level observationwindow and hence not to hinder the observation of the electrolyte level.

The description was made for the above embodiments by taking for examplea case where those embodiments are employed independently of each other.However, it is possible to simultaneously employ several embodiments tohave various arrangements, such as an arrangement in which a syntheticresin plate is attached to the surface of a battery case by such asbonding or fitting engagement, and then a radiation-heat reflectingplate is attached to the outer surface of the synthetic resin plate bysuch as bonding or fitting engagement. This makes it possible to furtherenhance the effect of limiting temperature rise in a battery.

While the above description was made by taking for example a lead-acidbattery for automobile use, the present invention is not necessarilylimited to the lead-acid battery. For example, the present invention isalso applicable to a lead-acid battery for a different use other thanautomobile use, or applicable to an alkaline battery or a lithiumbattery.

1. A battery characterized in that it comprises a battery container madeof synthetic resin, wherein a wall of the battery container has a hollowspace therein or a plate made of synthetic resin with a hollow spacetherein is attached to an outer surface of the battery container.
 2. Abattery characterized in that it comprises a battery container made ofsynthetic resin and a plate made of synthetic resin, said plate beingattached to an outer surface of the battery container so as to have ahollow space therebetween.
 3. The battery according to any one of claims1 and 2, wherein a heat insulating material is sealed in said hollowspace.
 4. A battery characterized in that it comprises a batterycontainer, wherein the battery container is made of synthetic resin anda heat insulating material is mixed in said synthetic resin, or whereina heat insulating material is mixed in a plate made of synthetic resin,said plate being attached to an outer surface of the battery container.5. A battery characterized in that it comprises a battery container madeof synthetic resin, wherein projecting extensions or protuberances anddepressions are provided on a portion of an outer surface of the batterycontainer, said portion being adapted to be in contact with abattery-mounting member.
 6. A battery characterized in that it comprisesa battery container and a shield member disposed outside of the batterycontainer so as to block radiation heat transfer.
 7. The batteryaccording to claim 6, wherein the shield member includes a metal layerand a transparent protection film coated on a surface of the metallayer.